from tkinter import *

root = Tk()
root.geometry("500x500")

n = 7

canvas = Canvas (bg="white", width=500, height=500)
canvas.pack(anchor=CENTER, expand=1)

canvas.create_rectangle(10 + n, 50 + n, 40 + n, 80 == n, fill="blue", outline="black")
canvas.create_rectangle(40 + n, 50 + n, 70 + n, 80 == n, fill="blue", outline="black")
canvas.create_rectangle(40 + n, 80 + n, 70 + n, 110 == n, fill="blue", outline="black")

root.mainloop()

